<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <title>水平框架</title>
</head>
<frameset rows="25%,50%,25%">
  <frame src="frame_a.html">
  <frame src="frame_b.html">
  <frame src="frame_c.html">
</frameset>
<body>

</body>
</html>